Abstract
Dihydrofolate reuctase from human osteosarcoma cell lines resistant to Methotrexate (MTX) were examined. MTX resistance in TE85 osteosarcoma sublines was produced by exposing cells to gradually increasing concentrations of MTX. Cloned sublines of MTX-resistant cells are maintained in media containing 10−8 (TE85/F.8), 10−7 (TE85/R7), or 10−6M MTX (TE85/R6). Partial purification of human dihydrofolate reductase from both sensitive and resistant osteosarcoma cell lines was achieved using folate-sepharose affinity chromatography. Although the TE85/R6 cell line was 120-fold more resistant to MTX than the MTX-sensitive cells, the amplification of enzyme activity was only 3.3-fold. Monoclonal antibodies raised against dihydrofolate reductase from a MTX-resistant subline of L1210 murine leukemia cells (Proc. Am. Assoc. Cancer Res. 26:229, 1985) cross-reacted with reductases from human cells. Immunostaining with these antibodies was used to rapidly visualize elevated amounts of dihydrofolate reductase in MTX-resistant osteosarcoma cells. Further delineation of the exact mechanisms(s) accounting for the MTX resistance in these human osteosarcoma cells is currently under investigation.
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Sato, J., Defrank, T. & Yee, A. DIHYDROFOLATE REDUCTASE FROM METHOTREXATE-RFSISTANT HUMAN OSTEOSARCOMA CELLS. Pediatr Res 21 (Suppl 4), 305 (1987). https://doi.org/10.1203/00006450-198704010-00830
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DOI: https://doi.org/10.1203/00006450-198704010-00830